// The MIT License (MIT)
//
// Copyright (c) 2016 Polidea
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

extension ObservableType {
    /// Absorbes all of events from a and b observables into result observable.

    /// - parameter a: First observable
    /// - parameter b: Second observable
    /// - returns: New observable which emits all of events from a and b observables.
    /// If error or complete is received on any of the observables, it's propagates immediately to result observable
    static func absorb(_ a: Observable<E>, _ b: Observable<E>) -> Observable<E> {
        return .create { observer in
            let disposable = CompositeDisposable()
            let innerObserver: AnyObserver<E> = AnyObserver { event in
                observer.on(event)
                if event.isStopEvent {
                    disposable.dispose()
                }
            }
            _ = disposable.insert(a.subscribe(innerObserver))
            if !disposable.isDisposed {
                _ = disposable.insert(b.subscribe(innerObserver))
            }

            return disposable
        }
    }
}
